The Classic Machinery Network

I have a bit of a problem with a smoky Perkins 4.236t in a wheel loader.

The engine was completely rebuilt, 3 years ago, new block as old one was porus, new pistons, liners, head, turbo overhaul, 1000hrs done since. Its not been a great rebuild, its smoky under low load high revs from new and now its got a constant wisp of smoke even at engine idle, white smoke rather than black or blue, and it appears to be getting worse.

Its got that much smoke a casual observer would say, something wrong with that engine or else its a lot of work done. however plenty power and no problem starting, and sounds good, idle speed is fine too. Smoke qty doesn't change ever after a few hrs working.

I dont think bores are glazed, it gets a workout everyday climbing a hill for 5 mins travelling on the road.

The smoke is also getting worse, I think. We dont seem to be using oil or water. The air filter and fuel filters are clean.

The injector pump and nozzles were reconditioned at the time of the rebuild. Its possible there was a mistake made as the engine rebuilder and installer were different people and injector pressure or timing got mixed up with a regular 4.236.......

Regular 4.236 seems to be 22-24degrees timing and 17.1MPA https://pruefberichte.dlg.org/filestora ... glisch.pdf

and 4.236t seems to be 16degrees and 23.1MPA. https://pruefberichte.dlg.org/filestora ... glisch.pdf

the heater in the inlet manifold not connected to fuel so no diesel dribbling in

Hi Aiden and welcome this appears to be a bit of a mystery, does it start easy enough? If it was over fueling I would have thought black smoke? Is there any other system that could let oil into the engine such as a hydraulic pump or a power steering pump? If so, if it is easy enough then just disconnect them (you may have to fabricate a temporary blanking plate) then run the engine and see if there is any difference? Let us know how you get on, this is all I can think of at this time but perhaps somebody else on here can make another suggestion.

Jeremy

Is the smoke similar to the sort of smoke you get out of an an old diesel before the engine fires?
Second question, is there a a fuelled air intake heater for cold starting?

essexpete wrote:Is the smoke similar to the sort of smoke you get out of an an old diesel before the engine fires?
Its not a chug chug chug of smoke its a steady stream
50% of what you see here https://www.youtube.com/watch?v=_EPKJXS0Oy8 and a steady stream, rather than chug chug chug, its a steady stream I guess due to the turbo mashing it all up


Second question, is there a a fuelled air intake heater for cold starting?

One of these I presume you mean. https://www.youtube.com/watch?v=NeDvCVS38hk

There was, we took out the pipe during the rebuild so no diesel getting in there https://www.youtube.com/watch?v=NeDvCVS38hk the flame heater is still there plugging the hole in the intake manifold. Just thinking outload given that we have taken away the pipe, is it possible that the turbo is losing pressure through the diesel inlet hole in the heater I wonder, I must check.

What is supposed to stop the diesel flowing into that, I think it is just gravity fed from the filter bowl.

Jeremy Rowland wrote:Hi Aiden and welcome this appears to be a bit of a mystery, does it start easy enough? If it was over fueling I would have thought black smoke? Is there any other system that could let oil into the engine such as a hydraulic pump or a power steering pump? If so, if it is easy enough then just disconnect them (you may have to fabricate a temporary blanking plate) then run the engine and see if there is any difference? Let us know how you get on, this is all I can think of at this time but perhaps somebody else on here can make another suggestion.

Jeremy

Really easy to start, Starts on the button, hydraulic pump is powered from the flywheel, brake pump is attached where the power steering pump usually is, but thats no where near the combustion

If timing was off one degree would it be responsible I wonder, was thinking of loosening mounting bolts and trying the rotate the pump body. Turn it say 2mm toward the engine which would advance the timing 2degree or thereabouts from the current timing marks.

If the injectors were set wrong a regular 236 is 17MPA v 23MPA for turbo injectors could it give me these symptoms.

Anyone know what the timing should be is it the same for a 4.236 and 4.236t

Aiden, it would not hurt to try and alter the pump timing, just make sure that you mark it first so you can reset it correctly, however if it is getting worse as you say then I suspect that something else may be amiss.

Jeremy

Jeremy Rowland wrote:Aiden, it would not hurt to try and alter the pump timing, just make sure that you mark it first so you can reset it correctly, however if it is getting worse as you say then I suspect that something else may be amiss.

Jeremy

Yes I will have a go at that I think, Im just wondering whether to advance or retard.

And from what I read moving on the mounting holes 1mm or thereabouts is equivalent to 1 degree in the timing is the rule of thumb I think.

I suspect you may be right on somthing else amiss

Gave a good wash a few weeks ago and found i had a leak in the manifold feeding the turbo, so new gaskets and fixed that- air side is 100percent now. Engine definitely running better.

Still not quite right.....

Current situation, - post warmup with no load on the engine I give it a bit of a revving, I get a decent cloud of black smoke, more than i should have.
Still smoking a bit under load too...........

Anyone any experience with rotating the pump to adjust the timing, its a regular CAV pump

Not to state the obvious but have you tried running it briefly with the air cleaner disconnected?